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(ModeL) H. B. WILLIAMS. DRAFTSMANS CURVE.

No. 447,593. Patented Mar. 3,1891.

NITED STATES HENRY B. IVILLIAMS, OF ROCHESTER, NEW YORK, ASSIGNOR OFONE-HALF TO LEMUEL A. JEFFREYS, OF SAME PLACE.

. DRAFTSMANS CURVE.

SPECIFICATION forming part of Letters Patent No. 447,593, dated March 3,1891.

Application filed July 11, 1889. Serial No. 317,246. (ModeL) To aZZ whomit may concern:

Be it known that I, HENRY B. WILLIAMS, of Rochester, in the county ofMonroe and State of New York, have invented a certain new and usefulImprovement in Draftsmens Curves; and I do hereby declare that thefollowing is a full, clear, and exact description of the same, referencebeing had to the drawings accompanying this specification.

My improvement relates to draftsmens curves, and is designed to providea rulingedge which can be bent or adjusted to any desired form and fixedin that position, thereby avoiding the difticulties that occur in theuse of a stiff curve.

The invention consists in the construction and arrangement of partshereinafter described and claimed.

In the drawings, Figure 1 is a plan view of the instrument with thecurve set in 8 form. Fig. 2 is a cross-section of the same in line 00 asof Fig. 1. Fig. 3 is an elevation of a portion of the device, looking inthe direction of the arrow in Fig. 1.

The instrument is composed of a base A, a

' flexible strap B, and a set of arms 0 C C.

The base A consists of a stiff segmental bar, which may be cast orotherwise formed, and has preferably a raised rib a, which forms thesupport for the arms.

The strap B is a strip of spring-steel or other suitable material whichwill readily bend, but will recover its straight form when freed fromrestraint.

The arms 0 O O are thin strips of metal provided with longitudinalslots 1) h. The front ends of the arms are pivoted to lugs c c, whichare riveted to the flexible rule B, and the rear ends rest flat on topof the base A and are secured thereto by set-screws (Z d, which passthrough the slots 1) b of the stays. \Vashers f f are inserted'betweenthe setscrews and stays, and these washers are made of differentthickness near the ends of the instrument, as shown in Fig. 3, forapurpose presently to be described. The base A lies flat on the surfacewhere the drawing is to be made, While the rule B stands cdgewisothereon, as shown in Fig. 2.

To adjust the curve the rule B is bent to the desired form, and theset-screws (Z (Z are then turned down to clamp the stays C O on the baseA. In this condition the rule is held stiff and can be transferred fromone place to another and be used any desired number of times. In bendingthe rule to make the adjustment the stays slide forward or back on thebase and are retained in place by the screws. By the use of washers f fof different thicknesses the rear ends of the stays O O are elevated,some higher than the others,

so that they will lap over or past each other without interfering inmaking sharp bends.

By the use of this device the desired curve can be made throughoutitswhole length and claim, simply and broadly, a bed-plate provided withslotted arms and set-screws for conforming to a curved surface.

What I claim as new, and desire to secure by Letters Patent, is-

In a draftsmans curve, the combination of So a base, a flexible rule,stays pivoted at one end to the rule and resting at the other on thebase, set-screws for securing the stays to the base, and washers betweenthe stays and base,

said Washers varying in thickness under the different stays, as and forthe purpose specified.

In witness whereof I have hereunto signed my name in the presence of twosubscribing witnesses.

HENRY B. IVILLIAMS.

Witnesses:

L. A. J EFFREYS, R. F. OSGOOD.

